GB309552A - Manufacture of acid wool dyestuffs - Google Patents

Abstract

309,552. I. G. Farbenindustrie Akt.- Ges. April 12, 1928, [Convention date]. Addition to 299,721. Samples furnished. Naphthalene derivatives.-Acid wool dyes of the kind described in the parent Specification are obtained by the action of reducing agents in aqueous solution on nitronaphthalimides or their N-alkyl, N-aralkyl or N-aryl derivatives. If un- Sulphonated bodies are used as parent materials, the reducing agents employed are such as simultaneously cause the entrance of a sulpho-group, for example, a hydrosulphite or bisulphite. Water-soluble orgarnic solvents, such as alcohol, are advantageously added to the aqueous solutions. The parent materials may be made by oxidizing nitro-acenaphthenes or by directly nitrating naphthalic anhydride, and condensing the resulting nitro-naphthalic anhydrides with ammonia or an aliphatic or aromatic amine. In an example, 4-nitronaphthalic-N-methylimide is reduced with hydrosulphite; the product dyes animal fibre in very even clear yellow tints; the methylimide may be replaced by the corresponding ethyl- or phenyl-imide, and the hydrosulphite by bisulphite. The Specification as open to inspection under Sect. 91 (3) (a) includes further examples in which (1) 4-nitronaphthalimide is reduced with hydrosulphite, the product dyes wool a greenishyellow tint. and (2) 4-nitro-1 : 8-naphthalic-4<1>-sulphophenylimide is reduced with hydrosulphite; the product dyes wool a clear yellow tint. This subject-matter does not appear in the Specification as accepted.